In recent years, realization of a ubiquitous information environment where information can be accessed “at anytime and anywhere, and by anyone” has been often proposed. To meet this need, the present inventors of the invention of this application have already proposed an information support system allowing a user to obtain information from an information transmission device provided at any position in the surrounding environment simply by placing his/her user terminal at a proper position and in a proper direction. The user terminal therein is a simple, small and light terminal which needs no battery, and this good mobility and attachability of the battery-less terminal allowing easy information access (see Nonpatent Documents 1 to 3 and Patent Document 1, for example).
Further describing the information support system, as shown in FIG. 9, for example, the battery-less terminal (1), carried by or attached to a user, has a photoelectric conversion means (11) such as a solar cell for receiving an optical signal which is strength-modulated and emitted by an information transmission device (2) and converting the optical signal to an electric signal and also has a sound output means (12) such as an earphone and a head phone for outputting the electric signal converted by the photoelectric conversion means (11) as sound. The information transmission device (2) placed in the environment side has a light source (21) of the optical signal and a modulation means (22) for modulating the strength of the optical signal in accordance with an electric signal of sound information to be transmitted. This system achieves ubiquitous information support wherein a user can freely acquire and listen to his/her necessary sound information by simply directing his/her own battery-less terminal (1) toward the information transmission device (2). In the battery-less terminal (1), the sound output means (12) is driven by the electric signal obtained by the photoelectric conversion means (11) and the electric signal is directly replayed as sound. The alternating current component which an information signal is assigned to is used for driving the sound output means (12) and the direct current component generated simultaneously by the photoelectric conversion means (11) is not used. Thus, sound output is implemented with no battery, entirely by the alternating current component.
Furthermore, as exemplified in FIG. 10, in order to allow the detection of the position of a user, the information support system further provides a position detection device (3) which uses an infrared imaging in the environment side. The battery-less terminal (1) further has a reflection means (13) such as a retroreflector for reflecting infrared light emitted by the position detection device (3). And, the position detection device (3) is provided with an infrared light source (31) of infrared light, an infrared imaging means (32) for detecting infrared light reflected and returned by the battery-less terminal (1) and a position detection means (33) for detecting the position of the battery-less terminal (1) based on an infrared image captured by the infrared imaging means (32). Thus, this system achieves interactive information support wherein the user can obtain sound information and at the same time the environment side can obtain user position information.
FIG. 11 is a schematic and external view of a more specific example of the above information support system. In this example, the battery-less terminal (1) is an earphone type terminal integrally equipped with a solar cell (11A) serving as the photoelectric conversion means (11), an earphone (12a) serving as the sound output means (12) and a retroreflective sheet (13a) serving as the reflection means (13). More specifically, a plate-like light transmitting/receiving portion comprising the retroreflective sheet (13a) around the solar cell (11a), the two substantially on one plane, is attached to an ear attachment portion having the earphone (12a). And, the plate-like light transmitting/receiving portion and the ear attachment portion are unified into one terminal body so that the photo-receptive plane or the solar cell (11a) and the photo-reflective plane of the retroreflective sheet (13a) face in the direction of user's line of sight when the earphone (12a) is attached to a user's ear. Inside the terminal, there is only a wire (not shown) for connecting the output terminal of the solar cell (11a) and the input terminal of the earphone (12a), and no power supply such as a battery for driving the earphone (12a) is installed therein. This is because the earphone (12a) is directly driven by an electric signal obtained by the solar cell (11a) to output the sound as described above and does not require any other power supply. The earphone type battery-less terminal (1) can in this way achieve more superior terminal attachability, and a user who is a terminal user can obtain information support from the environment side more easily.
On the other hand, the information transmission device (2) in the environment side is equipped with an LED (21a) serving as the light source (21) of optical signals and also equipped with a modulator circuit (22a) serving as the modulation means (22), which is installed inside the device cabinet or externally and separately of the device. The modulator circuit (22a) performs the strength modulation of the optical signal by, for example, changing the driving voltage of the LED (21a) in accordance with the voltage level of a sound signal generated by a sound source (not shown), which is a source of sound information to be transmitted. The LED (21a), for example, may be an infrared LED which can emit a sufficient amount of light or may include an array of LEDs in order to obtain more amount of light for a required transmission distance. In accordance with the purpose of use, the LED (21a) preferably has directivity such that the light can be emitted only in a specific direction and may include an LED array at the focus position of a reflection mirror having a parabola reflective plane, for example.
The position detection device (3) is integrally equipped with an infrared LED (31a) serving as the infrared light source (31) and an infrared camera (32a) serving as the infrared imaging means (32), and further equipped with a position detector (33a) serving as the position detection means (33), which is installed inside the device cabinet or externally and separately of the device. Since the retroreflective sheet (13a) of the battery-less terminal (1) reflects received light parallel to the incident direction, the infrared camera (32a) and the infrared LED (31a) are disposed close to each other in the integrated position detection means (33) in order to capture the reflected and returned infrared light accurately.
Then, as illustrated in FIG. 12, when a user wearing the earphone type battery-less terminal (1) in his/her ear enters into the environment where the information transmission device (2) and the position detection device (3) are prepared and directs him/herself toward those environment-side devices, the user can listen to various sound information such as voice, music and sound signals and also can inform his/her position to the environment side. FIG. 12 illustrates an application example in an art museum, where a user can hear voice guide information on each picture.
As described above, the information support system already proposed by the inventors of the present invention realizes the information support with significantly superior characteristics of ubiquitous and interactivity.
[Nonpatent Document 1] Takuichi NISHIMURA et al, “Interactive Joho Shien notameno Mudengen Kogata Joho Tanmatsu (Compact Battery-less Information Terminal for Interactive Information Support)”, Shingakugiho, The Institute of Electronics, Information and Communication Engineers, Nov. 22, 2002, pgs. 1 to 6.
[Nonpatent Document 2] Takashi NAKAMURA et al, “Mudengen Kogata Tsushin Tanmatsu CoBIT niyoru Kinkyori Joho Shien no Jitsugen (Realization of Short Distance Information Support with Compact Battery-less Information Terminal CoBIT)”, Report of Information Processing Society of Japan Study Group, Information Processing Society of Japan, Jun. 8, 2002, 2002-ICII-3, pgs. 1 to 7.
[Nonpatent Document 3] Takuichi NISHIMURA et al, “Mudengen Kogata Tsushin Tanmatsu wo Mochiita Ichini Motozuku Joho Shien Sisutemu (Information Support System based on Position with Compact Battery-less Information Terminal)”, Report of Information Processing Society of Japan Study Group, Information Processing Society of Japan, Jan. 28, 2002, 2002-ICII-2, pgs. 1 to 6.
[Patent Document 1] PCT/JP02/12306